Variable volume constant throw terminal re-heat system

ABSTRACT

A system for temperature conditioning the air of a room in a building. The system is particularly directed towards eliminating drafty conditions and/or uncomfortable temperature variations, predominantly noticeable heretofore as the typically conventional system cycles during the summer months in operable response to a thermostatic switch located in the room. Some of the features of the present invention contributing towards the accomplishment of the above include structure for by-passing variable volumes of the supply air away from the room while forcing the remaining volume of air into the room with the same velocity as when the total volume of air was directed into the room, structure for reheating a portion of the aforementioned reduced volume of cool air so that the confluence of cooler air and re-heated air is forced into the room, again with the same velocity as when the total volume of cool air was directed into the room, and structure for admitting varying volumes of re-heated air into the room, i.e., up to 100 percent re-heated air, for warming an overcold room, e.g., a room having been cooled to a comfortable summer daytime temperature which is considered too cool for comfort in the evening or nighttime, and for heating the room during the winter months.

United States Patent Avery [451 Mar. 21, 1972 [72] Inventor: Gilbert 11. Avery, 1475 Central Avenue, Memphis, Tenn. 38104 [22] Filed: Nov. 19, 1970 [21] App]. No: 91,072

[52] US. Cl ..l65/22, 98/38, 165/ 30,

' 165/35, 165/103, 236/13 [51] Int. Cl ..F24f3/06 [58] Field ofSearch 165/22, 30, 35, 36, 37,103;

[56] References Cited UNITED STATES PATENTS 2,327,664 8/1943 Otis ..98/33'A 3,122,202 2/1964 Scharres ....236/l3 X 3,252,509 5/1966 Keegan ..l65/l03 3,433,295 3/1969 Avery ..l65/35 VARIABLE VOLUME CONSTANT THROW TERMINAL RE-HEAT SYSTEM Primary Examiner-Albert W. Davis, Jr. Attorney-John R. Walker, 111

[5 7] ABSTRACT A system for temperature conditioning the air of a room in a building. The system is particularly directed towards eliminating drafty conditions and/or uncomfortable temperature variations, predominantly noticeable heretofore as the typically conventional system cycles during the summer months in operable response to a thermostatic switch located in the room. Some of the features of the present invention contributing towards the accomplishment of the above include structure for by-passing variable volumes of the supply air away from the room while forcing the remaining volume of air into the room with the same velocity as when the total volume of air was directed into the room, structure for re-heating a portion of the aforementioned reduced volume of cool air so that the confluence of cooler air and re-heated air is forced into the room, again with the same velocity as when the total volume of cool air was directed into the room, and structure for admitting varying volumes of re-heated air into the room, i.e., up to 100 percent re-heated air, for warming an overcold room, e.g., a room having been cooled to a comfortable summer daytime temperature which is considered too cool for comfort in the evening or nighttime, and for heating the room during the winter months.

10 Claims, 4 Drawing Figures Patented NIarcB 21, 1972 FIG.

FIG. 2

00000000 COO 0000 FIG. 3 7' e9 67 63 53 FIG. 4

Rm 1/ E a H m z W Y B a Q VARIABLE VOLUME CONSTANT THROW TERMINAL RE-I-IEAT SYSTEM BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to forced air temperature conditioning systems having ducts for circulating the conditioned air to the various rooms or zones in a building. More specifically, the invention relates to apparatus for controlling and distributing the conditioned air supplied to each room or zone of the building.

2. Description of the Prior Art In a conventional re-heat system all the supply air is cooled low enough so that any zone or space can be conditioned when that zone re-heat system is off. The other zones that are calling for less than maximum cooling are maintained at a satisfactory temperature by re-heating the supply air with conventional heat transfer equipment such as a hot water coil. This type system is expensive to operate in that all the air must be cooled to design conditions and then re-heated to satisfy the room thermostat.

An improvement over a straight re-heat system is disclosed in my U.S. Pat. No. 3,433,295 which provides the following advantages over a straight re-heat system:

a. When the space is calling for heat, only part of the supply air is heated and the rest of the air is by-passed back to the air handling unit. Inasmuch as the air that is by-passed is already cooled, it reduces the load on the air-handling unit.

b. The damper arrangement that controls the heating coil is superior to the straight re-heat system in that the heat delivered by the heating coil is proportional to the damper position. This is not true when the heat output is controlled by a valve throttling the water flow to a coil. Also, there is less maintenance since there is no valve on the heating coil to cause trouble.

c. The air velocity out of the supply grille remains relatively constant throughout the cycle. This maintains proper air circulation in the conditioned space.

There are, however, distinct disadvantages in practicing my U.S. Pat. No. 3,433,295 patent:

a. It is necessary to size the grille so that it may handle the cooled air through one portion thereof and the heated air through a separate portion thereof, e.g., if the design engineer determined that it is necessary to move 100 cubic feet per minute, to be necessary for heating, the grille would have to be sized so as to move 150 cubic feet per minute, because only part of the grille is used for cool air and a separate part is used for heated air.

b. The downstream side or back side of the heat coil is not thermal sealed from the moving air stream which results in heat pickup from the heat coil as the colder air passes adjacent thereto when the thermostat is demanding full cold air. Obviously, this reduces the efficiency of the system since the heat pickup from the coils reduces the transfer of B.t.u.s from the room. Additionally, the heat loss adds to the operational cost of the system since the coils are automatically maintained at a predetermined temperature, i.e., when the temperature drops in the heat coils, the boiler automatically is fired up to return the temperature therein back to a predetermined level.

c. When the temperature of the ambient air adjacent the thermostat is cooler than the setting thereof, the system immediately directs some of the cool air through the heat coils. This, too, does not lend itself to an economical operation because heat energy is used when it may not have been necessary.

SUMMARY OF THE INVENTION The present invention is directed towards overcoming the disadvantages and problems relative to previous air conditioning systems. The apparatus of the present invention generally includes a duct for carrying air from the air supply source to the room, a unit interposed in the duct, heat coils or the like positioned internally of the unit, preferably adjacent the grille leading into the room, a heating damper for gradually admitting a portion of air linearly through the heating coils and for selectively stopping the passage of air through the heating coils, acooling damper, and structure for proportionally varying the volume of air passing through the grille or into the room.

When the system is calling for full cooling, the heating coil is completely isolated from the cold supply air by the heating damper on the inlet side of the heating coil and by the cooling damper on the leaving side of the heating coil. 7 By sequencing the heating damper with the cooling damper, no heat is supplied to the room until the cooling damper reaches a predetermined position, as selected by the design engineer, i.e., the heating damper remains closed while the thermostat actuates the cooling damper to control the volume of cool air entering into the room. The velocity of the air entering into the room is maintained constant by the structure for proportionally varying the volume of air passing through the grille, e.g., a by-pass damper or the like. In other words, one such system might be designed so that half of the air is being delivered to the room and the other half is by-passed back to the air supply source, the cooling damper and by-pass damper operably responding to a pneumatic thermostat or the like. However when this arrangement does not satisfy the setting on the thermostat, the heating damper, also operating responding to the thermostat, gradually opens so as to admit a portion of the cool air over the heat coils. The confluence of the heated air and the cool air adjacent the grille opening into the room causes the temperature therein to rise gradually so as to meet the demands of the thermostat.

The apparatus of the present invention utilizes the whole face of the supply grille when the system is calling for full cooling, i.e., the area of the supply grille can be reduced considerably over the prior systems, e.g., 66 percent, when using the specifications described earlier.

A further advantage of the system of the present invention is directed towards certain air conditioning systems where there is no heating medium available certain times of the year, e.g., most schools shut ofi their boilers in the summertime. When this happens, with conventional re-heat systems, the space is overcooled. However, the control system of the present invention provides structure so that is there is no heat media available, the heating damper can remain closed during these periods. Since the cooling damper in response to the thermostat will go closed, as the space temperature drops, the likelihood of overcooling the conditioned room will no longer be a problem.

During the winter months when the thermostat is calling for full heat, the cooling damper automatically remains closed, and the heating damper operably responds to the thermostatic demands so as to move sufficient heated air through a portion of the grille with the same velocity as when the entire grille face was used.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational sectional view of the variable volume constant throw terminal re-heat unit, showing the various dampers positioned as they would appear for delivering maximum cooling.

FIG. 2 is identical to FIG. 1, except that the various dampers are shown positioned for delivering minimum cooling and no heat.

FIG. 3 is identical to FIGS. 1 and 2 except the various dampers are shown in full lines positioned for delivering full heating, and in broken lines in an intermediate position.

FIG. 4 diagrammatically depicts the unit of the present invention, showing it as it would appear when delivering full cooling in a typical environment arrangement or system.

DESCRIPTION OFTI-IE PREFERRED EMBODIMENT The variable volume constant throw terminal re-heat unit or apparatus of the present invention is herein character referenced by the numeral 11 and is intended to be a part of a system 12 (FIG. 4) for temperature conditioning the air of a room 13 is in a building. System 12 generally comprises a conventional cooled and pressurized air supply source 15, a grille 17 opening into the room 13, a duct 19, heating coils 21, a heating damper valve 23, a cooling damper valve 25, and structure for proportionally varying the volume of air passing through the grille 1 7, e.g., a by-pass damper valve 27 or the like. It should be pointed out that the bypass valve 27 (FIG. 4) leads into a duct 29 communicating with the air supply source 15. However, an air return duct 31 having an opening at the one end thereof leading into the room 13 communicates with the air supply source in a typical manner so as to receive a volume of ambient air from the room 13 and return it to the air supply source. Accordingly, the air return duct 29, as depicted in FIG. 4, preferably would connect to the air return duct 31 at a convenient location along the length thereof, i.e.,

obviating the necessity of providing an independent duct system for returning the by-passed air.

It should be pointed out that the apparatus 11, as herein described, is conveniently directed towards servicing a single room 13. However, in actual practice the apparatus 11 would more than likely be most beneficial in a large building, e.g., a hotel or school or the like, having numerous rooms with each room having a unit 11 connected in to a master pressurized air supply source. Additionally, in the course of describing the apparatus 11, various values of air pressure will herein be referred to, e.g., 7% lb. per square inch or 15 lb. per square inch. However, these values are intended to be representative values and are conveniently used to described the structure apertaining thereto. In other words, these values are given by way of illustration and not limitation.

The system 12 includes a temperature responsive device, e.g., a pneumatic room thermostat 33 which causes pressure to vary linearly with a change in temperature. The pressure output of the thermostat has the usual operating range, e.g., to l lb. per square inch. The thermostat 33 preferably is connected to a constant air pressure source, e.g., a motor-driven air pump 35 or the like. by a conduit or flexible tubing 37.

The unit 11 of the present invention is depicted in the drawings as being interposed in duct 19 immediately adjacent the grille 17 which opens into the room 13, with a short portion 19 of duct 19 being between grille 17 and unit 11. However, it should be understood that the unit 11 may be used with an indefinite length of supply duct interposed between the unit 11 and the grille 17 without departing from the spirit and scope of the present invention.

The unit 11 is provided with a boxlike or sleevelike housing 39, which is open at the opposite ends thereof and defines a passage 42 for air to flow therethrough. Housing 39 has structure obvious to those skilled in the art adapted to be fitted at the one end to the duct 19 and at the other end to the duct 19'. A fixed baffle plate 40 extends transversely across the interior of housing 39 as depicted in the drawing to divide the passage 42 generally into an upper flow path 39' and a lower flow path 39". The heating, cooling, and by-pass damper valve 23, 25, 27 preferably being formed from sheet steel or the like, have a leaf or blade-type typical construction, i.e., they have the usual structure for pivotal attachment to the housing 39, obvious to those skilled in the art.

Referring now to FIG. 1 of the drawings wherein the preferred positioning of the valves 23, 25, 27 is depicted when the thermostat 33 is demanding full cooling, when the unit 11 is delivering full cooling, the heating damper valve 23 is closed so as to deflect the air, diagrammatically depicted by a plurality of arrows, upwardly away from the heating coils 21. Additionally, the cooling damper valve 25 is in the open position so that the entire face of the grille 17 is utilized to deliver this maximum volume of air into the room 13. Further, the by-pass damper 27 is in a closed position so that the maximum volume of air is permitted to move on through the unit 11.

It should be pointed out that the valves 23, 25, 27, as herein disclosed, are controlled by individual pneumatic actuators, yet to be disclosed, and the sequencing of the system is accomplished by selecting an actuator having the proper spring range to accomplish the desired function. However, this same sequence may be accomplished by using a single actuator having suitable mechanical linkage attached thereto without departing from the spirit and scope of the invention, i.e., the structure for the aforementioned single actuator having mechanical linkage to sequentially perform the intended functions herein is obvious to those skilled in the art. In this regard, a pneumatic actuator 41, being operably responsive linearly between 0 and 7% lb. per square inch, having an actuator arm 43, is mechanically connected to the heating valve 23 in any well known manner, e.g., a mechanical linkage member 45. The one end of the member 45 is fixedly attached to the valve 23 in any well known manner, e.g., welding or the like, so that when the actuator 41 drives the actuator arm 43, the linkage member 45 moves the valve 23 from a closed position (FIG. 1) to an open position (FIG. 3), in a manner well known to those skilled in the art.

The actuator 41 is in communication with the thermostat 33 pneumatically through a conduit 47 (FIG. 4) extending from the actuator 41 to a valve 49, thence through the valve 49 to a conduit 51 (having junctions therein leading to structure yet to be disclosed) thence to the thermostat 33. In other words, the valve 23 is operably responsive to the thermostat 33, i.e., when the pneumatic pressure in the conduit 47, 51 drops below 7% lb. per square inch, the damper valve 23 is caused to move proportionally from a closed position toward an open position as the pneumatic pressure drops.

Additionally, a pneumatic actuator 53, being operably responsive to pneumatic pressures in the range between zero to'l5 lb. per square inch, includes an actuator arm 55 which linearly moves to and fro in response to the amount of pressure which the thermostat 33 is putting out, i.e., a conduit 57 connects the actuator 53 with the previously described conduit 51. In other words, the damper valve 25 maintains an open position (FIG. 1) when the pneumatic pressure in the conduits 51, 57 is 15 lb. per square inch and as the pneumatic pressure in the conduits 51, 57 gradually diminishes to 7% lb. per square inch, the damper valve 25 gradually moves to an intermediate position, substantially as depicted in FIG. 2, and as the pressure in the conduit 51, 57 gradually diminishes to 0 lb. per square inch, the damper valve 25 gradually moves to the closed position shown in solid lines in FIG. 3. Obviously, the actuator arm 55 and the damper valve 25 are interconnected with suitable mechanical linkage, e.g., members59, 61. The member 61 has the one end thereof fixedly attached to the damper 25 in any well known manner, e.g., welding or the like, and the other end thereof is pivotally attached to the one end of the member 59 and the other end of the member 59 is pivotally attached to the actuator arm 55, which includes structure well known to those skilled in the art.

Further, a pneumatic actuator 63, being operably responsive to a range of pneumatic pressures between 7 /2 and 15 lbs. per square inch communicates with the thermostat 33 through the aforementioned conduit 51 and a junction thereto including a conduit 65. The actuator 63 includes an actuator arm 67 mechanically connected to the damper valve 27 through a pair of mechanical linkage members 69, 71, i.e., the one end of the member 71 is fixedly attached to the damper valve 27 in any well known manner, e.g., welding or the like, and the other end thereof is pivotally attached to the one end of the member 69, the other end of the member 69 is pivotally attached to the actuator arm 67, which includes structure well known to those skilled in the art. In other words, when the pressure in the conduits 51, 65 is 15 lb. per square inch, the damper valve 27 is in the closed position (FIG. 1) and as the pressure in the conduits 51, 65 gradually diminishes to 7% lb. per square inch. the actuator 63 causes the damper valve 27 to gradually move .to

the open position (FIGS. 2 and 3). It should be noted that the damper valve 25 seals the heating coil 21 against heat loss as the cooler air moves adjacent thereto en route to the grille 17, i.e., when the damper valve 25 is in the open position (FIG. 1).

Referring now to FIG. 2 of the drawings wherein it may be seen that the cooling valve 25 has moved to an intermediate position and the by-pass valve 27 has moved to the open position so that approximately 50 percent of the total volume of air is by-passed to the air supply source and the remaining 50 percent moves on through the unit 1 l and is discharged therefrom through the grille 17. In other words, as the thermostat 33 calls for less cooling, the cooling damper 25 moves up across the face of the grille 17 so as to close off the discharge opening and at the same time the by-passed damper 27 starts to open and pass the excess air back to the air supply source 15. The complementary action of the dampers 25, 27 maintain a constant velocity of air flow from the grille 17 as the volume emitting therefrom varies. It should be understood that the above disclosure, being based on by-passing 50 percent of the air back to the air supply source when the unit 1 l is in a minimum cooling no-heat condition (FIG. 2) is given by way of illustration in explaining the operation of the device and is not to be so limited since other values may be used without departing from the spirit and scope of the present invention.

An important feature of the unit 1 1 of the present invention is sequencing the heating damper 23 with the cooling damper 25 so that the temperature in the room 13 can be gradually reduced without consuming heat energy, i.e., heat is not used until the cooling damper 25 reaches a predetermined position as selected by the design engineer. FIG. 2 of the drawings shows the dampers 23, 25, 27 in an optimum position for the unit 11 to deliver minimum cooling. It should be observed that the heating damper 23 is still closed and that the cooling damper is at an intermediate position, the by-pass damper 27 is wide open, and that half of the air (arrows) is being delivered to the room 13 and half is by-passing back to the air supply source 15. When the valves 23, 25, 27 are positioned as depicted in FIG. 2 of the drawings, the output of the thermostat 33 preferably would be at its mid-range, e.g., 7% lb. In other words, the output from the thermostat 33 has dropped from 15 lb. for the condition depicted in FIG 1 of the drawing to 7% lb., i.e., the pressure in the interconnected conduit 47, 51, 57, 65 has not reached the operable range for the actuator 41 so the valve 23 remains closed, the pressure has reached the lower limit for the actuator 63 so that the valve 27 is fully open, and the pressure has reached a mid-point in the operable range for the actuator 53 so that the valve 25 is in an intermediate position.

The unit I] of the present invention is depicted in a full heating condition in solid lines n in FIG. 3 of the drawings. The unit 11 includes a baffle assembly 73 for maintaining optimum air velocity through the grille 27 as the cooling damper 25 moves into the range of positions between a predetermined intermediate position and the closed position and the heating damper 23 is in the range between the closed position and the open position It should be understood that the baffle assembly 73 is optional and particularly would not be recommended when the output from the unit 1 1 empties into a length of supply duct rather than into an adjacent grille 17.

It will be noted that there are positions of valves 23, 25 illustrated in FIG. 3 in broken lines as at 23, 25' which are intermediate positions between that shown in solid lines in FIGS. 2 and 3 in which positions 23', 25' the thermostat 33 is calling for some heating. In this example shown in broken lines, the thermostat is calling for one-half heating and the air pressure is 3% lb. It might appear that the low velocity heated air moving through lower flow path 39" would not carry or produce the blow that the higher velocity cold air that is moving through upper flow path 39' and coming out of the top of the unit would produce. However, this is not the case since induction and convection will rapidly mix the warm air with the cold air stream to provide essentially the same throw. The streams will mix by induction since the slow moving warm air will be induced by the higher velocity cold air and the warm air will rise by convection into the cold air stream. With this operation, the velocity of the air out of the bottom of the unit (i.e., that moving through lower flow path 39") has little to do with the total throw out of the box. When the heating damper 23 is in the full heat position and cooling damper 25 is closed, there is still essentially the same throw since now there is all of the air discharging out of the bottom of the unit at the desired velocity to produce the proper throw out of the unit.

Baffle assembly 73 includes not only fixed baffle plate 40, heretofore mentioned, but also a movable baffle plate 77 which extends from side to side of the housing 39 and is pivotally attached to fixed baffle plate 40 in a manner obvious to those skilled in the art. The plate 77 has at least an operable position (FIG. 3) and a non-operable position (FIG. I) and is spring biased to the operable position by a spring 79 in a manner obvious to those skilled in the art. The baffle assembly 73 also includes a flexible length of chain 81 for holding the movable baffle plate 77 in a predetermined operable position, i.e., the chain 81 has one end thereof fixedly attached to the plate 77 and the other end thereof fixedly attached to the housing 39 in a manner obvious to those skilled in the art.

It should be understood that when the unit 11 is delivering full heat (solid line position of FIG. 3), the output air pressure from the thermostat 33 would be nil, i.e., diminished to 0 lb. per square inch. Obviously, the actuator 63 has not changed from the position depicted in FIG. 2 since the pressure, 7% lb. per square inch, was at the lower limit, accordingly, lowering of the pressure to 0 lb. per square inch in the system has no further effect upon the position of the damper 27. However, the zero pressure in the system causes the actuator 41 to move to its opposite limit so that the heating damper 23 is fully open and the actuator 53 is moved to its opposite limit so as to cause the cooling damper 25 to move to the fully closed position. In other words, using the values conveniently referenced above, the unit 11 is by-passing percent of the supply air back to the air supply source 15 and re-heating the remaining 50 percent of the air, when the thennostat 33 is calling for full heat. It should be understood that this ratio is a variable and is normally selected by the design engineer. For example, in some instances it may be desirable to by-pass two-thirds of the air back to the air supply source and move only one-third of the air through the heating coil 21 when the unit 11 is in the full heat output condition.

It should be understood that the above disclosure depended upon having the dampers 23, 25, 27 positioned at their limits when in actuality the air pressure output of the thermostat 33 is a gradual changing pressure and the conduits 47, 51, 57, 65 interconnect the actuators 41, 53, 63 so that this gradual pressure change slowly moves the appropriate dampers 23, 25, 27 through infinite intermediate positions so that a smooth transition of air displacement takes place, i.e., the valves 25, 27 do not abruptly move from the position depicted in FIG. 1 to the position depicted in FIG. 2, nor do the valves 23, 25 abruptly move from the position depicted in FIG. 2 to the broken line positions and then to the solid line positions depicted in FIG. 3. In other words, after the unit 11 passes through the 50 percent by-pass and 50 percent delivered to the grille 17 and the thermostat 33 calls for more heating, the heating damper 23 starts to open and the cooling damper 25 continues to move across the face of the grille 17 until the cool air is completely stopped. At this time, the heating damper 23 has fully opened so that the volume of air moving through the grille 17 must first travel through the heat coils 2]. Further, the velocity of the air is maintained constant by the baffle plate 77 to effectively reduce the cross sectional area of the housing 39.

In some air conditioning systems, there is no heating medium available at certain times of the year, e.g., most schools shut off their boilers in the summertime. When this happens, with conventional re-heat systems, the room 13 would probably overcool. A feature of the present invention obviates this problem by incorporating a pair of valves 49, 83. The position of the valve 49 (FIG. 4) in the system 12 was previously disclosed. The valve 83 has the one end thereof communicating with the air pump 35 and the other end thereof communicating with the conduit 47 leading into the actuator 41. When the heating medium or, in this case, the coils 21 is/are operating the valve 49 is fully open, and the valve 83 is fully closed so that the output pressure from the thermostat 33 is delivered through the valve 49 to the actuator 41 and the output from the pump 35 is delivered only through the conduit 37 as previously described.

However, when the heating medium or the boilers (not shown) which deliver the heat to the coils 21 is/are shut down so that the coils 21 are not heated, the valve 49 is completely closed, and the valve 83 is fully opened so that the actuator 41 is isolated from the output pressures of the thermostat 33. In other words, the object is to keep the heating damper 23 in the fully closed position as shown in FIG. 1 and 2. Accordingly, the lb. pressure from the air pump 35 is constantly applied to the actuator 41 which causes the heating damper 23 to remain closed, the pressure being over the required 7% lb. per square inch, as previously disclosed. In this arrangement, the cooling damper 25 and the by-pass damper 27 are still interconnected and function in the same manner as previously described, i.e., operably responding to the thermostat 33. In other words, since the cooling damper 25 will go closed, as the temperature in the room 13 drops, overcooling the room 13 I will no longer be a problem.

It should be understood that the by-pass damper 27 is optional, i.e., the damper valve 27 being just an example of how the pressure in the supply air system could be maintained constant. This could be accomplished in any of the well known techniques, e.g., providing a damper adjacent the blower, i.e., a component part of the pressurized air supply source 15, and this damper could be opened and closed in like manner as the previously described by-pass damper 27 operably responds to the thermostat 33.

Obviously, during the winter months the refrigeration system (not shown), which is a part of the cooled pressurized air supply source 15, would preferably be shut down so that the air supply introduced to the unit 11 through the duct 19 would be ambient air or cooler air returned from the room 13, in a manner obvious to those skilled in the art. An object of the unit 11 is that all of the air in the room 13 is constantly being changed in the winter and the summer so as to remove smoke and/or other objectionable odors and to maintain a fresh air environment therein. This is accomplished principally by varying the volume of air moving into the room 13 in a unique manner of maintaining a constant velocity thereto so that the air always moves a predetermined distance into the room away from the grille 17 and gradually settles down so that no cold blasts of air are felt by the people who might be in the room 13.

Although the invention has been described and illustrated with respect to a preferred embodiment thereof, it is not to be so limited since changes and modifications may be made therein which are within the full intended scope of this invention.

I claim:

1. A variable volume constant throw terminal re-heat system for temperature conditioning the air of a room in a building comprising an air supply source, grille means opening into said room, duct means for communicating said air supply with said grille means, a unit including a housing defining a passage for air to flow therethrough, said housing being interposed in said duct means, means for heating said air supply, said heating means being positioned internally of said housing, heating damper valve means having infinite positions for selectively and gradually admitting a portion of said air supply linearly through said heating means and for selectively stopping the passage of said .air supply through said heating means; cooling damper valve means having at least an open position, intermediate positions and a closed position for thermal sealing the downstream side of said heating means when in said open position, for selectively reducing the cross sectional area effectively of said passage when in said intermediate positions, and for selectively stopping the passage of air to said grille means, except the air which may be admitted through said heating means, when in said closed position; and means for proportionally varying the volume of air passing through said housing to maintain a constant air pressure adjacent to and upstream of said heating and cooling damper valve means irrespective of the positions thereof.

2. The apparatus of claim 1 which includes means dividing said passage into an upper flow path and a flower flow path containing said heating means, with said lower flow path being disposed below said upper flow path to cause .the heated air to exit from said grille below the cooler air.

3. A variable volume constant throw terminal re-heat system for temperature conditioning the air of a room in a building comprising a cooled pressurized air supply source, grille means opening into said room, duct means for communicating said pressurized air supply source with said grille means, a unit including a housing defining a passage for air to flow therethrough, said housing being interposed in said duct means, means for heating said air supply, said heating means being positioned internally of said housing downstream from said pressurized air source, heating damper valve means having infinite positions including an open position and a closed position for selectively and gradually admitting a portion of said air supply linearly through said heating means as said heating damper valve means is moved from said closed position to said open position and for selectively stopping the passage of said air supply through said heating means when moved to positions including at least an open position, intermediate positions and a closed position for thermal sealing the downstream side of said heating means when in said open position to insulate said heating means from said air supply as it passes adjacent thereto, for selectively reducing the cross sectional area effectively of said passage when in said intermediate positions, and for selectively stopping the passage of air to said grille means, except the air which maybe admitted through said heating means, when in said closed position; control means including thermostatic switch means positioned in said room operably coupled to said cooling damper valve means for actuating said cooling damper valve means, means interconnecting said heating damper valve means with said cooling damper valve means for sequentially actuating said heating damper valve means with said cooling damper valve means as said cooling damper valve means responds to said thermostatic switch means, and means for maintaining a constant air pressure within said housing as said heating and cooling damper valve means sequentially respond to said thermostatic means.

4. The apparatus of claim 3 in which said means interconnecting said heating damper valve means and said cooling damper valve means is arranged so that said heating damper valve means remains in said closed position as said cooling damper valve means moves between said open position and a predetermined one of said intermediate positions and said heating damper valve means being also arranged to move from said closed position to said open position as said cooling damper valve means moves from said one of said intermediate positions to said closed position, said movement of said heater damper valve means being proportionate with said movement of said cooling damper valve means.

5. The apparatus of claim 4 in which said heating means, said heating and said cooling damper valve means are located terminally of said duct means adjacent said grille means and are arranged so that the total area of said grille means passes air therethrough when said heating damper valve means is in said closed position and said cooling damper means is in said open position.

6. The apparatus of claim 3 in which is included air return duct means having an opening at the one end thereof leading into said room, said opening communicating with said cooled pressurized air supply source for receiving a volume of ambient air from said room and thereby returning it to said air supply source, and said means for maintaining a constant air pressure within said duct means includes by-pass damper valve means adjacent said cooling damper valve means for bypassing a variable volume, having predetermined limits, of cooled air from said housing and being operable responsive to actuation of said cooling damper valve means.

7. The apparatus of claim 6 in which said by-pass damper valve means includes by-pass duct means communicating with said air return duct means for recirculating said variable volume of cooled by-passed air through said pressurized air supply source.

8. The apparatus of claim 6 in which is included means for holding said heating damper valve means in said closed position while said cooling damper valve means and said coacting by-pass damper valve means continue to be operably responsive to said thermostatic switch means.

9. The apparatus of claim 5 in which is included baffle means adjacent said grille means for maintaining optimum air velocity through said grille means as said cooling damper valve means is in the range between said predetermined intermediate position and said closed position and said heating damper valve means is in the range between said closed position and said open position.

10. The apparatus of claim 9 in which said baffle means has at least an operable position and a non-operable position, and in which is included spring means for urging said baffle means from said non-operable to said operable position, and means for holding said baffle means in a predetermined position defining said operable position.

1F t IF t i 

1. A variable volume constant throw terminal re-heat system for temperature conditioning the air of a room in a building comprising an air supply source, grille means opening into said room, duct means for communicating said air supply with said grille means, a unit including a housing defining a passage for air to flow therethrough, said housing being interposed in said duct means, means for heating said air supply, said heating means being positioned internally of said housing, heating damper valve means having infinite positions for selectively and gradually admitting a portion of said air supply linearly through said heating means and for selectively stopping the passage of said air supply through said heating means; cooling damper valve means having at least an open position, intermediate positions and a closed position for thermal sealing the downstream side of said heating means when in said open position, for selectively reducing the cross sectional area effectively of said passage when in said intermediate positions, and for selectively stopping the passage of air to said grille means, except the air which may be admitted through said heating means, when in said closed position; and means for proportionally varying the volume of air passing through said housing to maintain a constant air pressure adjacent to and upstream of said heating and cooling damper valVe means irrespective of the positions thereof.
 2. The apparatus of claim 1 which includes means dividing said passage into an upper flow path and a flower flow path containing said heating means, with said lower flow path being disposed below said upper flow path to cause the heated air to exit from said grille below the cooler air.
 3. A variable volume constant throw terminal re-heat system for temperature conditioning the air of a room in a building comprising a cooled pressurized air supply source, grille means opening into said room, duct means for communicating said pressurized air supply source with said grille means, a unit including a housing defining a passage for air to flow therethrough, said housing being interposed in said duct means, means for heating said air supply, said heating means being positioned internally of said housing downstream from said pressurized air source, heating damper valve means having infinite positions including an open position and a closed position for selectively and gradually admitting a portion of said air supply linearly through said heating means as said heating damper valve means is moved from said closed position to said open position and for selectively stopping the passage of said air supply through said heating means when moved to positions including at least an open position, intermediate positions and a closed position for thermal sealing the downstream side of said heating means when in said open position to insulate said heating means from said air supply as it passes adjacent thereto, for selectively reducing the cross sectional area effectively of said passage when in said intermediate positions, and for selectively stopping the passage of air to said grille means, except the air which may be admitted through said heating means, when in said closed position; control means including thermostatic switch means positioned in said room operably coupled to said cooling damper valve means for actuating said cooling damper valve means, means interconnecting said heating damper valve means with said cooling damper valve means for sequentially actuating said heating damper valve means with said cooling damper valve means as said cooling damper valve means responds to said thermostatic switch means, and means for maintaining a constant air pressure within said housing as said heating and cooling damper valve means sequentially respond to said thermostatic means.
 4. The apparatus of claim 3 in which said means interconnecting said heating damper valve means and said cooling damper valve means is arranged so that said heating damper valve means remains in said closed position as said cooling damper valve means moves between said open position and a predetermined one of said intermediate positions and said heating damper valve means being also arranged to move from said closed position to said open position as said cooling damper valve means moves from said one of said intermediate positions to said closed position, said movement of said heater damper valve means being proportionate with said movement of said cooling damper valve means.
 5. The apparatus of claim 4 in which said heating means, said heating and said cooling damper valve means are located terminally of said duct means adjacent said grille means and are arranged so that the total area of said grille means passes air therethrough when said heating damper valve means is in said closed position and said cooling damper means is in said open position.
 6. The apparatus of claim 3 in which is included air return duct means having an opening at the one end thereof leading into said room, said opening communicating with said cooled pressurized air supply source for receiving a volume of ambient air from said room and thereby returning it to said air supply source, and said means for maintaining a constant air pressure within said duct means includes by-pass damper valve means adjacent said cooling damper valve means for by-passing a variable volume, Having predetermined limits, of cooled air from said housing and being operable responsive to actuation of said cooling damper valve means.
 7. The apparatus of claim 6 in which said by-pass damper valve means includes by-pass duct means communicating with said air return duct means for recirculating said variable volume of cooled by-passed air through said pressurized air supply source.
 8. The apparatus of claim 6 in which is included means for holding said heating damper valve means in said closed position while said cooling damper valve means and said coacting by-pass damper valve means continue to be operably responsive to said thermostatic switch means.
 9. The apparatus of claim 5 in which is included baffle means adjacent said grille means for maintaining optimum air velocity through said grille means as said cooling damper valve means is in the range between said predetermined intermediate position and said closed position and said heating damper valve means is in the range between said closed position and said open position.
 10. The apparatus of claim 9 in which said baffle means has at least an operable position and a non-operable position, and in which is included spring means for urging said baffle means from said non-operable to said operable position, and means for holding said baffle means in a predetermined position defining said operable position. 